While the South Beach Diet and the Atkins Diet continue to tally book sales -- an estimated 30 million to date -- 11 health organizations have teamed up to dispel what they call popular misconceptions about the low-carbohydrate approach and to warn about the risk of its long-term use.

The Partnership for Essential Nutrition, led by former U.S. Surgeon General C. Everett Koop's Shape Up America! group, cautions that studies show the low-carb approach can starve the brain of carbohydrates, produce constipation and other gastrointestinal problems, reduce energy levels and cause difficulty concentrating.

In the long run, the groups warn, the regimens can stress the kidneys and increase the risk of liver disorders, gout, coronary heart disease, diabetes, stroke and several types of cancer.

"Low-carbohydrate diets conflict with decades of solid scientific research that clearly encourages us to reduce saturated fat and boost fruit, vegetable and fiber intake," said Barbara Moore, president and CEO of Shape Up America!

These diets have "promoted the simplistic belief that individuals can solve their weight and related health problems by eliminating one nutrient from the diet, or at least drastically reducing intake of that nutrient: carbohydrates," noted Alison Rein, assistant director of food and health policy for the National Consumers League, one of the groups in the partnership. The partnership received a $25,000 grant from Weight Watchers to produce a public service announcement for TV about the potential dangers of low-carb diets.

Not only is this "magic bullet" approach wrong, Rein said, but "it has also likely led to decreased consumption of fresh fruit and vegetables, whole grains, low-fat dairy foods and fiber."

Colette Heimowitz, director of education and research for Atkins Nutritionals, dismissed those concerns, saying that research "continues to support the safety of low-carb diets as an option for weight loss and maintenance." She said that Atkins Nutritionals has created a food ladder to help guide consumers to add back carbohydrates after the induction phase of the Atkins diet, when carbs are most strictly limited.

The partnership, Heimowitz said, "is funded by big industry and Weight Watchers. They have millions of dollars behind them. . . . These are the companies whose sales are plummeting and who are also launching their own low-carb products."

Moore said 10 of the 11 health groups in the partnership have contributed only time, not money. Nine are nonprofit, including one that is funded by the federal Centers for Disease Control and Prevention. Two are university affiliated. Shape Up is footing the bill for the partnership. Moore said the group has received money for other projects from Tanita (makers of a body fat scale), Gerber Food Products (to sponsor a one-day meeting in Washington on childhood obesity) and the Florida Department of Citrus (for a meeting on breakfast nutrition).